Testing Alcohol Tolerance

[Kriznac]

I have some yeast that I have captured and know it can make a good beer but now I want to find out its alcohol tolerance. I am planning on making a high gravity wort out of some DME and letting it ferment. After it is done fermenting is the ABV the alcohol tolerance? What should the OG be for this type of experiment? Any Ideas?

 

[Oldsock]

I would start the wort with an OG matching what you considering using the yeast for. I don’t see a reason to go through the effort of determining the absolute limit. The issue is that if you start the OG too high the yeast will have problems getting going.

 

[COLObrewer]

I have some yeast that I have captured and know it can make a good beer but now I want to find out its alcohol tolerance. I am planning on making a high gravity wort out of some DME and letting it ferment. After it is done fermenting is the ABV the alcohol tolerance? What should the OG be for this type of experiment? Any Ideas?

I would make a couple (or more) small test batches, start with a gravity a couple points lower than previous experienced abv. Add extract to each in increments (shake after each addition) maybe even add yeast nutrients, keep them on the warm side. When they stop fermenting (No gravity movement for a few days after adding extract) keep adding extract to one for a couple more times, trying to get it to ferment further.

You have to keep track of the potential gravity of each addition, when you're satisfied the higher gravity batch won't go any further, add up all the additions to get the calculated OG for each, test the FG of both (All). If everything went well, both (All) batches should have near the same ABV, an average of that is close to your yeasts tollerance.

Keep on brewing my friend